Ordnance



Aug. 14, 1945. R. J. HOCHSTETLER 2,382,225

ORDNANCE Filed Dec. 8, 1942 4 Sheets-Sheet 1 1945. R. J. HOCH'STETLER' 2,382,225

ORDNANCE Filed Dec. 8, 1942 4 Sheets-Sheet 2 k Aug. 14, 1945.

R. J. 'HOCHSTETLER ORDNANCE Filed Dee. 8, 1942 4 Sh ets'-S heet 5 QM-J n y E K n w 1 ms m m .w T. m1 m Aug. 14, 1945. J. HOCHSTETLER 2,382,225

)QRDNANCE Filed Dec. 8, 1942 4 Sheets-Sheet 4 \NKii 1 INVENTOR.

Patented Aug. 14, 1945 ORDNANOE Robert J. Hochstetler, Westport, Conn, assignor to Amalgamated Ordnance & Ammunition Machinery Company, New York, N. Y., a proprietary company of New York Application December 8, 1942, Serial No. 468,182

4 Claims.

.. This invention relates to ordnance and more particularly to a novel and useful gun of the muzzle-loading mortar type.

Objects and. advantages of the invention will be set forth in part hereinafter and in part will be obvious hereirom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

Fig. 1 is a side elevation of a gun and mounting embodying the invention;

Fig. 2 is a front elevation of the same;

Fig. 3 is an enlarged fragmentary vertical section on line 33 of Fig. 1;

Fig. 4 is a fragmentary sectional detail on line 4-4 of Fig. 2,'showing the base portion in elevation; 1

Fig. 5 is an enlarged fragmentary sectional detail of the breech end of one-of the gun barrels;

Fig. 6 is an elevation, with parts in section, of a projectile to be fired in the gun; and

Fig. 7 is a fragmentary, partlydiagrammatic section, with parts in elevation, of a modification of the invention.

Objects of the invention are to provide a new and improved muzzledoading mortar-type gun, wherein the possible rate of fire is very greatly increased over known types of muzzle-loading mortars and wherein said improved muzzle-loading gun is designed and adapted for very rapid and accurate traversing and elevating and depressing through a great vertical angle, whereby it is capable of use in anti-aircraft operations, particularly against low-flying planes on divebombing and ground attack missions. By virtue of the invention it is possible to provide a very rapid firing weapon capableof delivering high explosive, time-fuse-controlled, fragmentationtype projectiles of large caliber and capacity at any angle or site from near the horizontal to the complete vertical. a

The present invention is an improvement on that disclosed and claimed in the co-pending application of Clare H. Armstrong and Alexander J. Stuart, Jr., Serial No. 443,378, filed May18, 1942. One important feature of the invention is the provision of means for releasing air and other gases from the breech of the gun except during the firing of a round. By means of automatically-operated valve mechanism, I provide that air and gas mayescape from the breech'of the gun except when the projectile is seated therein and thereafter until the projectile has been propelled from the muzzle by the propellent gases. This feature of the invention has many advantages as hereinafter set forth. Primarily it increases the speed of loading by eliminating resistance to fallof the projectile toward the breech occasioned by the entrapment of air and building up of counter-air pressure; it enables loading at very much lower angles of. site than now possible; it removes the difliculty or'centering the projectile to strike the firing pin with-the percussion cap; eliminates fluttering of the projectile falling through the barrel; and also permits the use of a much closer fitting projectile, thereby increasing the potential muzzle velocity and. efiective range of the weapon.

The present invention provides further improvements in the relationship between said valve mechanism and the firing pin whereby it is assured that firing cannot take place until the valve is securely seated, thus preventing escape of gas between the valve and its seat with consequent loss of muzzle velocity. This feature of my invention also increases the safetyof use of the gun by making it possible to withdraw the firin pin and/or valve mechanism or back same away from a projectile seated in the breech of the mortar in the event 01 a misfire or a broken pin so that danger of handling a mlsfired projectile is largelyreduced. I

All of these advantages of the invention are combined with great simplicity of construction for gun, mount and ammunition, simplicity of operation and maintenance 1 and exceedingly low cost of construction. As to the latter'no rifiing of the barrels is required; no expensive breech mechanism, and no fire control mechanism which is usually very expensive and delicate. The weapon also is quite light in weight so that it may easily be transported and be fired from a truck or other vehicle.

It will be understood that the foregoing general description and the following detailed description as well are exemplary and explanatory but. are not restrictive of the invention. Referring now in detail to. the present preferred embodiment of the invention, illustrated by way of example in. the accompanying drawings, the invention is shown in connection with a mount breech end II in a receiver block 12 having a. cylindrical, threaded interior which has threaded engagement with the externally-threaded portion [3 at the breech end of the barrel. The muzzle end of the bore is slightlyichamfere'd at [4 to facilitate introduction .of'the projectile." In general the construction of said barrel is similar to that used in the Stokes infantrymortar.

The receiver mechanism is designed toac'commodate two such barrels mounted and fixed inparallel relation as shown in Fig. 2 or, if desired, a single. such barrel may be centrally. positioned on' the mounting. For this purpose three receiver blocks l2 are provided, each of said blocks being formed with a flat flangedbacking l5. The backing portions I5 of the receiver blocks are each bolted to the underface of a fiat mounting plate l8 and are equally spaced across the face thereof. As shown inFig. 2, the two flanking receivers Ma and l2b are provided with barrels Illa and 1017 respectively while thecentral receiver I is idle, but it will be understood that a single barrel of identical form may be mounted in the receiver block I20 and the twin. barrels on either side omitted. iAdditional supportfor axial thrust along the barrels is provided by a pair of ribs l1. and 19 which are welded to an underface of the plate I8 and project at right angles therefrom to underlie the bottom face of the receiver block [2. As shown in Fig. 2 there is a pairofsaid ribs I1 and I9 so positioned with respect to each .of the receiver blocks [2a, 12b and I20. p

The embodied means for providing angular variable support forthe gun barrels, as previously stated, comprises -a flat circularvrotatable platform 20 on whichthe receiver plate I8 and the attached receivers and. barrels are. mounted for horizontal rotation or traversing movement with the platform and with, respect to which they are angularly movable in vertical planes. Referring first to the mounting for permitting vertical planar or elevating and depressing movement of the barrels, the lower portion of plate I8 is provided with apivot block fixed to and projecting at right angles downwardly at the bottom face of said plate [8. Saidpivot block 25 is provided with a horizontalb'ore 26 for rotary support on a horizontal pintle or hinge pin 21. Said hinge pin extends from either side of the block 25' anduthe extending ends thereof are journaled in suitable journal blocks 28. Said journal :blocks are integrally fixed to a base plate 29 which in turn is bolted to a thrust plate. 30 which lies upon and is fixed to the upper surface of the platform 20 at the center thereof. An upstanding lip 3| isformed in said thrust plate to contact with the rearv edge of plate 29 and thereby to secure same from the horizontal component of the recoil of the gun.

The embodied means for permitting horizontal rotation or traversing movement of base platform 20 comprises primarily a ball hearing at the circular periphery of said plate. The. plate 20 is provided with adownwardly-disposed vertical flange at its periphery. An upper raceway 36 for the ball bearing is fixed in the angle formed between said flange and the under surface of the plate. The lower raceway 31 is similarly fixed to the upper surface of a stationary base plate 38 which underlies and is substantially co-extensive with the plate 20. A horizontally-projecting guard lip 39 may extend at the periphery of said plate 38. Balls 40 are mounted between the upper and lower raceways and are held in position by the usual cage 4|. A

" dust seal or gasket 42 may be formed between theperiphery of the lower race. and the inner face of flange 35.

Additional vertical rotational support is provided at the center of platform 20 for said plat form and the parts attached thereto. As embodied, a horizontal reinforcing plate 45 is seated on and fixed to the upper surface of base plate 38 centrally thereof. A central vertical post 46 is reduced and threaded at its bottom end 4'1. and thus seated in an appropriate threaded opening at the center of the superposed plates and 38. A self-alining ball bearing is mounted on said plates 45 and 38 and about said post 46; said ball bearing being positioned and designed to provide the central support for the platform 20 as previously stated. Said ball bearing comprises an aligning washer 48 mounted on reinforcing plate 45 by an intervening flat washer 49. The lower race of the ball bearing comprises the annular member 50, the lower surface of which is spherically-shaped to rest upon the conforming upper face of washer 48. The upper ball race of the bearing comprises the annular member 5| which also surrounds the post 46 and rests upon the balls 52 of the bearing. The ball bearing assembly above-described is housed within a cup-shaped casing 55 which is fixed to and depends from the undersurface of the platform 20. An outer spaced annular wall 56 also depends from the under surface of said platform and surrounds the bearing assembly as will be clear from Fig. 3. Lateral thrust support for the central ball bearingassembly is provided by an upstanding annular wall 59 fixed to the upper surface of plate 45 and having rotary surface engagement with the depending portion of the cup 55. The post 46 extends upwardly through aperture in plate 30 and into a recess 51 in plate 29, the latter being shaped to loosely'enclose the enlarged head 58 on the post.

Means are provided for imparting controlled traversing rotation to the platform 20, same preferably to be actuated manually and as designed is intended to provide very rapid rotary movement to the platform, its occupants and other equipment thereon while at the same time the amount of manual power requiredis very small. For this purpose the platform 20 is adapted to be rotated on its ball bearings by the driving action of a geared pinion 60, Said pinion meshes with teeth 6! formed on the annular flanged member 62 which is fixed to the periphery of theplate 45. Pinion 6!] is at the lower end of stub shaft 65 which extends through a suitable aperture in the platform 20 and is journaled in a bracket 66 fixed to said platform. To the upper end of stub shaft 65 is keyed a bevel gear 61 which is meshed with beveled gear 68 on horizontal stub shaft 69, the latter being supported in the upstanding portion T0 of bracket 66. Sprocket wheel H is keyed to the hub of beveled gear 68 and is driven by sprocket chain 12.

The embodied means for imparting driving force to the above-described sprocket gearing for traversing movement comprises a hand wheel 80 which is fixed to one end'ofihorizontal shaftsl, on which is keyed a sprocket wheel 82 engaging the upper reaches of the-vertically-looped chain I2. i The shaft 8! is journaled-in a vertical side bracket plate 85, the lower end of which iscurved inwardly at 86 and ther welded to the top surface of the plate I8. A suitable handle 81 projects inwardly from the face of the hand wheel 80 and is mounted-near the periphery thereof.

The gearing ratio between the. hand wheel. 80 and the gearing 60''6I is such that very rapid rotation of theplatform 2D and guns-thereon may 'be' effected by relatively easy turning movement of the hand wheel .by the operator, while not limited to any specific ratio. In the preferred form the gearing ratiois such that one complete traverse of the platform Ziivthroush 360 may be made in 10 seconds or less. Thus the traversing required for firing at anairplane crossing the gunners front at 400 M. P..II. and a range as short as 600 yards (a most extreme-condition) is well within theability of a gunner of average dexterity and strength. I

Referring now to the present preferred means for moving the gunor guns in the vertical plane to elevate and depress them, such angular motion is imparted to the gun-supporting plate is by means of a verticalbracket plate 90 which is substantially the same in construction as the opposite bracket plate 85 and is similarly curved at its bottom end 9| for fixed attachment to the top surface of plate I8. Angular motion is imparted to said bracket plate 90 by means of a hand wheel 93 connected .to said'plate by a horizontal shaft 94 which is journaled in a U-shaped yoke 95. The inner arm 96 of said yoke is fixed to the upper end of the plate bracket 99. Rotatably mounted on said shaft 94' between the arms of 'said bracket 95 is a pinion 91. which is geared to mesh with the gear 'teethi98 of a segmental rack 99. Said rack is formed on the upper arcuate edge of a vertical plate Illii, the bottom of which is secured to the upperlsurface of the platform 20. As will be clear from the drawings, rotation of hand wheel 93 by its inwardly projecting nan dle IGI causes the gear 91 to rotate in mesh with the rack and travel along the curved surface thereof and thereby to rock the plate I8 and the attached gun barrels and other parts about the horizontal axle or hing pin 21. The arc covered by the rack 99 is slightly greater than 90 so that the gun may be elevated from the horizontal position of maximum depression to the maximum elevation of complete vertical.

In the present preferred form the gear ratio for elevating and depressing motion is such that the entire are from vertical to horizontal can be accomplished in about four seconds, with ten turns of the hand wheel, butit will be understood that this is not limiting of the invention as previously explained. i l

Means are provided for positioning the gunner or operator controlling the traversing and vertical movementsof the gun orguns so that both hand wheels 80 and 93 may be simultaneously operated by the single gunner using both his hands while the gunner is seated in fixed relation to the axis of the barrel or barrelsIO regardless of what their angular position may be either vertically or in azimuth. This feature of the weapon I also is designed to place the gunner automatically in position at all times so that his line of sight is always parallel to the angle. of site of thebare rels. As embodied, the upper surface of the receiver-supporting plate I!) is made the seat of a chair for the gunner as shown diagrammatically in Fig. 1'. An elongated and suitable curved back Ill so that no matter how the gunner is traversed, elevated Or depressed,.he will always be seated in exactly that same relative position. If the gun is elevated to a full 90", the rear of the backrest I05 will come in contact with the upper surface of the platform I20 where the gunner reclines without discomfort and with no change in his relative position with respect to the barrels.

To facilitate ease of vertical angular movement in all positions, equilib-ratin-g springs may be provided between the barrels and the platform. As shown (Figs. 1 and 4), one end of a helical spring 200 is pivotally fixed to platform 20 by a tubular casing 2(II which is hinged at its bottom to a lug 202 on the platform by a hinge pin 203.; The

upper .end of the spring is similarly fixed to'the end of a telescoping tube 204 which is ivotally connected to plate I8 by lug 205 and pin 205. Thus the spring and telescoping casing act to balance the weight of the gunner as he tilts back and thus to ease the depression of barrels.

For greater convenience and security th gunner is preferably provided with foot supports or treadles I I0 and I II which are so positioned and connected to the remaining portion of the seat assembly as to further insure that the gunner will remain seated at all times in the right-angled position required. For this purpose each of the foot tre'adles is formed as the lower flange of a Z- shaped bracket having a right-angled riser portion H2 and a rearwardly inclined upper portion H3. The latter is rigidly attached to a depending member IIA, the upper end of which is pivot-ally connected to lugs I I5 on the under surface of the Plate I8 by a pivot pin I I6. Said foot support I I I thus normally hangs freely pivotally from thefront edge of the seat plate l8, but is prevented from swinging below the angle shown in Fig. 1 by a stop member. (not shown). When the barrel or barrels I0 are depressed below a certain angle, the edge I It at the rear of the foot treadle III will come against the upper surface of the platform 20 and thereafter the pivotal motion will permit same .to slide along said surface and thus allow the gunners legs to straighten out in front of. him as the barrels are further depressed and preferably a cleat Ill is provided on the treadle I I l for bracing the gunners heel and side plate H8 may be provided for confining his foot laterally. It will be understood that the construction of the foot rest member I II] is identical with that described for treadle I I I.

Sighting mean are positioned in the line of sight of the gunner whereby he substantially automatically is constrained to look through said such means but any known form of rear .area 'or forward area sight may be employed. The sighting tube I is positioned as stated by means of a curved bracket yoke I2I, the lower ends of which are fixed to the upper ends of the side plate brackets I85 and 90 respectively. The sighting tube I20 is supported by a rod I2I which may be adjustably held in an aperture in the top of bracket I2I by means of a wing bolt I22 or other suitable means. The yoke I2! also serves as a transverse strengthening member for the superstructure of the traversing or elevating member. A suitable projectile for the gun is somewhat diagrammatically shown in Fig. 6. As shown, same varies little from the presently-used infantry Stokes mortar projectile and comprises a tear drop shaped explosive-containing shell I having bourrelete rings I 3| at its maximum diameter. The lower or base end of the shell tapers to a cylindrical tail portion I32 to which is attached the propellin means, The latter comprises a plurality of radial vanes "I33 of known construction having flanged edges I34 and intermediate fire propellant holding openings I35. Said vanes are attached to a cylindrical core I36 into which the igniting cartridge I31 is inserted. The latter is substantially like a shot gun shell in construction, having a slightly re cessed base end I38 at the center of which is placed the conventional percussion cap I39. A plurality of openings I40 are provided in the wall of the core I36 for fire distribution. Increments of propellant I4I of conventional shape are shown positioned in the spaces between the vanes.

The nose end of the projectile is preferably provided with a time fuse I50. While the latter may be of several types I have found the conventional powder-train time fuse to be generally satisfactory. As is known, the times for this fuse may be set by hand simply by turning the fuse-setting ring I5I t0 the proper fuse setting as indicated by the graduations on said ring. Said fuse is bore safe, armed by set-back (i. e. by the initial impact of firing and not by rotation) such fuse also is self-destroying and preferably designed also to burst upon'impact as well as the time set for any point on the trajectory. The 1907, 21 second powder-train fuse is one having most of these features and could be used substantially without change in connection with the present invention merely by providing a somewhat weaker spring in its forward element so that it will be armed by a lesser set-back impact.

It will be understood that the gun and mount hereinabove described are illustrative of one embodiment with which the improved features of the present invention may be utilized but, inasmuch as said invention relates primarily to the improved construction of the firing pin and valve mechanism, it will be understood that same is also applicable to other types of mounts for muzzleloading gravity-operated mortars. For example, same may be used with the conventional Stokes type trench mortar as will be obvious Without further description.

In accordance with the invention I provide improved means for increasing the speed of loading and firing the muzzle-loading barrels I0 by relieving the air pressure which normally builds u as the mortar projectile is dropped into the muzzle of'the barrel. This feature of the invention is of great importance also because it permits loading at greatly reduced elevations because the speed of falling of the projectile into the barrel is sufficient to fire the cap even at a very slight angle of fall because the retardant effect of air pressure in the barrel is eliminated. The projectile also falls much more smoothly without wabbel or flutter as the rush of compressed air past the bourrelet is substantially eliminated. This in turn makes it possible to use a projectile which fits more closely into the bore of the barrel so that a greater effective propelling effect and muzzle velocity result. That is, the bourrelet ridges I3I may be machined to a closer fit relative to the bore, thus reducing escape of propellant gases past the sides of the projectile in the bore and thereby giving a greater initial propelling pressure. Another advantage of this feature of the invention is that residual gas in the breech end of the barrel from a previous firing is virtually eliminated as said gases escape from the breech end of the gun after the projectile has left the barrel. This is a very important factor in increasing the rate of fire and the, safety thereof because in normal practice of firing Stokes mortars with a closed breech the collection of residual gases inthe breech end was a serious handicap.

Referring now to the present preferred embodiment of means for so controlling the escape of air at the breech end of the barrel, such means are shown in detail in Fig. 5. As there shown the cylindrical threaded socket I60 of the receiver block I2 terminates in a shoulder I6I against which the bottom end I I of the barrel is seated when same is screwed down to the limit. A second annular shoulder I62 of reduced diameter is formed slightly below said shoulder I BI and within that an annular arcuate groove I63 to provide clearance for the lower'edge of the projectile fins. A central fiat annular raised portion I64 lies within said groove I63 and constitutes a table within which a valve seat is formed to receive the valve head I65 when the latter is seated. A tapered or conical valve seat I66 is formed inside the table I64, said seat terminating in a cylindrical opening I61 which extends downwardly through the block I2 for a substantial distance. Transverse air and gas ports I68 communicate with the cylindrical opening I61 and lead therefrom to the outside of the block I 2.

There are preferably at least four of said ports provided. Additional communications therefrom to the atmosphere are also provided by vertical conduits I69 which lead to the bottoms of said ports I68.

Means are provided for holding open the valve seat and cylinder I61 and the exhaust ports as described during all times when the gun is idle and except when the projectile is being fired. Accordingly, the valve head I65 has a flat upper face I10 which as previously stated is adapted to lie flush with the table surface I 64 when the Valve is closed. A conical portion I1I lies below said upper surface I10 and is shaped to fit exactly into and against the seat I66 when the valve is closed. The valve head therebelow is reduced to an elongated tubular stem portion I12 which is considerably less than the diameter of the interior diameter of the cylindrical opening I61. The lower 'end of said valve stem is threaded at I13 and is there engaged by the threaded interior of a cupshaped nut I14 and an intervening threaded washer I15 which abuts against the bottom face I'IB of the receiver block I2. The lower face of said cup-shaped nut I14 provides a seat for the upper end of helical expansion spring I11 which surrounds the lower part I 13 of the valve stem and .itor elevation and super-elevation extends downwardly therefrom so: that i s lower end re ts against theirs-tiers o a holl w c plilre member. maxed to th lower and i the firin pin Hi which p oje ts upwardly throu h the bore of theral e stern- These parts a e cased a cup' ik'e h usin i7 8, th u per and o hich'-is intsrio y th eaded atlifi to enga e the orrespondingly th eaded. and reduced promo i n p i I16 Of e ceiverbl'ockli. pring l isv quite w al; and tendso hold the al ead 55 n he pen-position only wh n-s gue t ntial force. is exerted toclose same. while on: stantly g n he lower end of he fir ng pin gains t e bottom of h using I In pe ion thecdesc dins p ojecti e. which fa s it its'bu t to ard the b ech-oi the ba rel, first strikes the elevated valv head surface ill; and pushes same'to the closed position against the prina Upon subsequent firing f h pr t expanding propellent gases in the breech chamber between the bourrelet rings of the projectile and the receiver block at the breech maintain the valve closed until the projectile has cleared the muzzle of the piece. Thereupon the escape of the gas immediately permits the spring ill to raise the valve and thus permit the accumulated gas to escape rapidly from the breech end of the barrel as well as the muzzle.

Means are provided for causing the projectile to be fired as soon as it reaches the bottom of the barrel and the valve head I65 is in closed position, but no earlier. For this purpose the firllg pin I86 is positioned to strike the percussion cap 139 of the projectile only when the latter has fully descended into the breech and closed or virtually closed the valve.

The lower end of the firing pin is fixed relative to the Valve stem by the downward pressure of spring l1! against the enlarged end portion 198 of the pin which is engaged by and seated against a threaded adjusting number H85 in the threaded bore H36" in the lower end portion of the cup member H8. The threaded end of the adjusting mem-- ber H35 projects beyond the bottom surface of said cup member and is there engaged and held by a check nut I87. By means of this construction, it will be clear that the firing pin is firmly held 11 position but may be advanced or retracted with respect to the bottom of the barrel so as to provide more or less projection thereof for firing operations. By turning of the nut I'M on the threaded portion H3 of the valve stem exactly the desired relation between the projecting end 182 of the firing pin and the settng of the valve may be arrived at by experiment, while it is also possible by such means to back off and entirely withdraw the firing pin, if need be, as in the case of a misfire.

The operation of the invention will be generally understood from the foregoing description. The gunner, from his seat, operates the elevating hand wheel with his'righ't hand and the traversing hand wheel with his left. He-continuously observes the field of fire through and around the sight from his fixed position in the seat. By practice and observation he quickly learns how to operate the h'and wheels so as to apply the proper lateral lead or deviation and the proper vertical angle He also can estimate the fuse settings for the changing ranges of the moving target and will call out such settings to the crew so that the proper fuse for the next shot will be out and the round loaded into 7 stablegunner l ad ng of th or er-of fifty rounds per minute per barrel regui erossible. When twin barre sare proided two l aders w llstand on the'p tfo m, one adjacent e t rrel -en eac will operate a described; under .thevsing remesimpli i y .d-l e to lead n f om .th scon asted with breech-load ng uns, load n s eas r: at; e ev ted a gles ath n ighborhoo of the ver ical than at at lower, ele ations such as. thirty degrees. Moreover, the contour of the gun exposed. to view is relatively very small because the breech may be kept very low, only separated from the ground b the thickness of traversing platform.

The great simplicity of the gun makes it cheaply producible in large quantities, While we small pressures and weights involved require no critical or strategic materials.

A modification of the invention is shown in Fig. 7, wherein 'is disclosedthe principle of utilizing a vacuum or low-pressure source for facilitating the fall of the projectile against the firing pin by venting the gaseous pressure between the breech end of the barrel and the falling projectile more rapidly than same would escape to the atmosph'ere through the valve ports provided as hereinabove described. As somewhat diagrammatically shown in Fig. '7, the valve and firing pin construction previously disclosed is provided with one or more gas-escape ports I68 which, instead of leading to the atmosphere, are connected to suitably arranged conduits 200 which lead to a source of low pressure such as the intake side 2M of a vacuum pump 202 or the like. Said pump may be operated by a suitable motor 203 or, if desired, may be actuated by other power means such as may be derived from the recoil of the firing, the rotation of the gun mount or the like. It will be understood that such low pressure attachment will increase pro tanto the rapidity of fall of the projectile and the scouring 0f accumulated gases after firing. v

The invention in its broader aspects is not limited to the specific mechanisms shown and de-' scribed but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificin its chief advantages.

What I claim is:

1. In a gun in combination a barrel having an open muzzle for receiving a projectile insertible at said muzzle and movable along the bore of the barrel toward the breech end thereof, a firing pin seated at the breech end of the barrel and adapted to be struck by the moving projectile when same reaches the breech end of the barrel, valve means normally lying in the path of the falling projectile between same and the firing pin,

said valve means being moved to close by the falling movement of the projectile whereby said valve is closed by the time the projectile comes into contact with the firing pin.

2. In a gun in combination a barrel Having an open muzzle for receiving a projectile insertible at said muzzle and movable along the bore of the barrel toward the breech end thereof, a firing pin seated at the breech end of the barrel and projecting thereabove sufliciently to contact the percussion capof the projectile when same has fallen to the bottom of the barrel,a gas escape port at the bottom of. the barrel, a valve normally held away from said port but movable to close same Upon contact with the falling projectile, said valve in its open position lying between the contact end of the firing pin and the falling projectile and, in its closed position, being below said projecting end of the firing pin.

3. In a gun in'combination a barrel having an open muzzle for receiving a projectile insertible at said muzzle and movable along the bore of the barrel toward the breech end thereof, a firing pin seated at said breech end of the barrel and projecting 'a short distance into said barrel,

a valve movable axially with respect to the barrel and the firing pin at'the breech end of the barrel, and a valve port at said end adapted to be closed by said valve, means for normally holding said valve open and in a position axially beyond the end of the firing pin, said valve being movable by force exerted axially toward the breech end of the barrel to close the port and thereby to expose the end of the firing pin.

4. In a muzzle-loading gun in combination a firing pin seated in the breech end of said gun and projecting upwardly therefrom toward the muzzle of the barrel, a tubular valve member slidably mounted for axial movement on said pin, a gas port in the breech adapted to be closed by said valve, means for holding said valve open and above the upper end of the firing pin.

ROBERT J. HOCHSTE'ILER. 

